Neurons, neuronal networks, and signaling within critical brain networks adhere to the concept of leanness. Essential functional networks for perception, movement, and communication in the healthy brain are designed to optimize time and energy in neuronal processing. These networks are characterized by an organized mapping of basic functions in close proximity and precise wiring, forming large-scale maps within an individual’s brain. The overall redundancy in the human brain allows for the recruitment of resources from anatomically connected reserve pathways, known as neural plasticity, enabling the brain to overcome lesions and disorders. From a neural network perspective, disruptions can impact overall neural functions. Considerable research has focused on understanding the determinants and mechanisms that compensate for brain lesions through plasticity—the adaptive ability of neurons and networks to modify their signaling properties. Despite these efforts, a significant gap remains between current basic research and individualized clinical applications. Studies involving individual mapping and neuromodulation in patients with well-defined brain lesions not only enhance the outcomes of operations but also offer a practical approach to understanding, visualizing, and modulating brain plasticity.